King Neptune

King Neptune is the king of the sea. He's the husband of Queen Amphitrite. He is arguably the most powerful person in the sea (with Poseidon). He is a bad tempered, fiery merman. He likes to shoot people with his flame shooting trident but Mindy (his kind-hearted daughter) often convinces him to have mercy. He is very defensive on the topic of his hair; he claims he is not bald, only thinning. He also covered his head with a paper bag, as seen in the image at the bottom right of the page. He was even too worried about his balding head to even notice Plankton's conquest of Bikini Bottom.
He used to be very youthful, having a full head of hair. When he's out of water, like in Party Pooper Pants, his hair is bleached. When he goes back, some of his aging continues. As seen in The SpongeBob SquarePants Movie, he's bald, or "thinning" as he puts it, although he's obviously bald. In SpongeHenge, it's revealed that he is sometimes called Poseidon, the Greek name for Neptune.

King Neptune changed considerably since his first appearance in the episode Neptune's Spatula, where he was youthful, muscular and had a long, illustrious hair. In this episode he claimed to be king of Atlantis, but in Atlantis SquarePantis Lord Royal Highness, or LRH for short, is king. His next appearance was in the episode Party Pooper Pants, where he was a real life person with white hair. The only explanation possible for these frequent appearance changes was given in the episode Krusty Towers, where Squidward asked for a change in his Krusty Towers Hotel room to the theme 'Neptune the XIV would be nice', when the makeover was complete it had a portrait of the original Neptune. This suggests that there has been more than one King Neptune and that there is a new one every time we see him. In Neptune's Spatula, King Neptune uses some powers such lightning bolts coming out from his fingers, size change, super strength and control things with magic. He is also able to spit out something he eats (in perfect condition) and eat it again.

Neptune is commonly referred to like God in regular episodes, which is a reference to that Neptune was the Roman god of the sea. Examples of this are characters saying "Oh, dear Neptune", "Neptune give me strength", "What in the name of Neptune?", "For the love of Neptune", or "Neptune's beard!".

In the episode Neptune's Spatula, Neptune has hair, mustache, beard, chest hairs, thick fingers, and a different crown. In The SpongeBob SquarePants Movie, Neptune is "thinning" and has a trident. As suggested previously, it is possible that these are, in fact, different individuals, as there may have been several King Neptunes who have succeeded the original series, or he possibly got older due to the fact that the movie takes place after the whole series.